3-isobutyryl-2-isopropylpyrazalo[1,5-a]pyridine (code No. KC-404) having a chemical structure shown below was invented by the present inventors and is a publicly known compound as disclosed in Japanese Patent Publication No. Sho 52-29318; U.S. Pat. No. 3,850,941; Brit. Pat. No. 1,378,375; German Pat. No. 2,315,801 and etc. Cerebral vasodilating and bronchodilating effects of KC-404 have been disclosed in the above patents. Our studies on KC-404 revealed that it has an inhibitory effect on the type I (immediate type) allergic reaction (The Japanese Journal of Pharmacology 33, 267-278, 1983; Folia pharmacologica japonica 83, 281-289, 1984; ibid. 83, 291-299, 1984). We found that KC-404 also inhibits the Arthus reaction (type III allergic reaction) in a series of the experiments to determine its effects on type II-IV allergic reactions (Folia pharmacologica japonica 83, 291-299, 1984). It is generally accepted that the drug possessing the ability to inhibit articular rheumatism is effective in the Arthus reaction. Thus, our continuous studies on KC-404 lead us to the present invention. ##STR1##
Articular rheumatism is a progressive disease with consequent economic disability, despite intensive treatment with rest, physical therapy, gold, salicylates, and other drugs. If the patient is severely ill and has fever, joint swelling, and intense pain, many expert physicians advise administration of corticosteroids without delay. The decision of embark upon a program of hormone therapy must be made with due consideration for the fact that corticosteroid therapy, once started, may have to be continued for many years or for life, with the attendant risks of serious complications such as fluid and electrolyte disturbances, susceptibility to infections, peptic ulcers, osteoporosis, a characteristic myopathy, psychosis, and Cushing's syndromes. The initial dose of corticosteroid should be small and increased slowly until the desired degree of control is attained. The symptomatic effect of small reductions should be frequently tested in order to maintain the dose as low as possible. Complete relief, however, is not sought. Thus, in the place of corticosteroid therapy or for the reduction of dose of corticosteroids, another useful anti-rheumatic agent, surely effective and safe, has been required.